1. Field of the Invention
The present invention relates to a system for detecting a location of a fault which might occur in a substation, and more particularly to a system for detecting a ground fault and a short-circuit fault which might occur in a bus section within a distribution substation and a transmission substation.
2. Related Art Statement
In the transmission substation, one or more input lines are connected to one or more bus bars and the bus bars are connected to a plurality of output lines or banks by means of transformers. In the input lines there are connected current transformers for detecting currents passing through the input lines and circuit breakers for interrupting the power supply, and in the bus bars there are connected disconnecting switches for disconnecting the bus bars. In order to detect the ground fault or short-circuit fault, each current transformer is connected to a ground fault detection relay and/or short-circuit fault detection relay. When a relay connected to a current transformer in a certain input line detects a fault, a circuit breaker connected in the relevant input line is opened and one or more disconnecting switches are operated to disconnect the output lines from the input line in which the fault has occurred. In an unattended substation, the output signals of the relays are supplied to a remote control station in which an operator can detect the fault at the substation in accordance with the output signals sent from the unattended substation. It should be noted that from the signals supplied from the substation, the operator can know whether the fault has occurred outside the substation or inside the substation. However, in the known supervisory system, the operator could not know a precise location of the fault within the substation. Therefore, in the unattended substation, the operator has to find an actual location of the fault by visually observing various equipments within the substation. In this case, until the operator finds the fault location, all the transformers in the substation have to be remained inoperative and thus the electric power supply is totally interrupted for a relatively long time over a very wide range. The same problem occurs not only in the transmission substation, but also in the distribution substation.